Electrical devices from polymer resins prepared with ionic catalysts

ABSTRACT

This invention relates to olefin polymers particularly suited to satisfying the dielectric properties required in electrical device use. The olefin polymers can be prepared by contacting polymerizable olefin monomers with catalyst complexes of Group 3-11 metal cations and noncoordinating or weakly coordinating anion compounds bound directly to the surfaces of finely divided substrate particles or to polymer chains capable of effective suspension or solvation in polymerization solvents or diluents under solution polymerization conditions. Thus, the invention includes polyolefin products prepared by the invention processes, particularly ethylene-containing copolymers, having insignificant levels of mobile, negatively charged particles as detectable by Time of Flight SIMS.

[0001] This Application is based on Provisional Application U.S. Ser.No. 60/172,737 filed Dec. 20, 1999.

TECHNICAL FIELD

[0002] This invention relates to polymeric products that areparticularly useful for electrical devices and to olefin polymerizationprocesses that use supported catalyst compounds where the catalysts areattached to support materials.

BACKGROUND

[0003] Common examples of electrical devices include wire and cableapplications. Typical power cables include one or more electricalconductors in a core that is surrounded by several layers that caninclude a polymeric semi-conducting shield layer, a polymeric insulatinglayer and another polymeric semi-conducting shield layer, a metallictape, and a polymeric jacket. Thus, a wide variety of polymericmaterials have been used as electrical insulating and semi-conductingshield materials for wire, cable, and numerous other electricalapplications.

[0004] Polymerized elastomer or elastomer-like polymers are often usedin power cables. Ethylene, C₃-C₁₂ α-olefin, and C₅-C₂₀ non-conjugateddiene monomers form these elastic materials. Polymers containingethylene, either homopolymers or copolymers with C₃-C₂₀, olefinicallyunsaturated comonomers, are also used as insulating layers orsemiconducting layers. See for example, U.S. Pat. Nos. 5,246,783,5,763,533, International Publication WO 93/04486, and generally,“Electric Insulation”, Kirk-Othmer Encyclopedia of Chemical Technology,4th Ed., pages 627-647 (John Wiley & Sons, 1993). Dielectric strength,electrical resistivity, electrical conductivity, and dielectric constantare all important characteristics for these applications.

[0005] Polymerization of olefinically unsaturated monomers is well knownand has led to the proliferation of elastomeric and plastic materials,such as polyethylene, polypropylene, and ethylene-propylene rubber.Catalyst compounds with bulky, stabilizing-ligand-containing metalcation components are now well known in the art. Examples includecyclopentadienyl-ligand-containing transition metal compounds (e.g.,metallocenes), bisamido- and bisimido-ligand-containing transition metalcompounds, as well as other metal compounds that are stabilized byincorporating bulky ligands. Cocatalyst compounds containing, or capableof providing, non-coordinating anions can be used to stabilize thetransition metal cations and maintain their cationic form rendering themsuitable for olefin oligomerization and polymerization, see for exampleU.S. Pat. No. 5,198,401. This and related references describemetallocene compound protonation by anion precursors to form stablecatalysts.

[0006] U.S. Pat. Nos. 5,427,991, and 5,643,847 specifically teach theuse of anionic complexes directly bound to supports through chemicallinkages to improve polymerization processes that are conducted underslurry or gas-phase polymerization conditions. See also U.S. Pat. No.5,939,347 which addresses protonating or abstracting cocatalystactivators bound to silica.

[0007] Low crystallinity ethylene-containing elastomers andethylene-containing polymers can be produced under gas-phase or slurryconditions, but are more typically prepared by solution polymerizationprocesses, in part because these polymers have good solubility incommonly used hydrocarbyl solvents see the supported-catalyst referencescited above. Examples include: U.S. Pat. Nos. 5,198,401 (above),5,278,272, 5,408,017, 5,696,213, 5,767,208 and 5,837,787; and, EP 0 612678, EP 0 612 679, International Applications WO 99/45040 andWO99/45041. Although each reference, in part, addressesethylene-containing polymers prepared with ionic catalyst compounds;preparing satisfactory electrical device polymers from these solutionprocesses has unsolved problems. Using noncoordinating or weaklycoordinating anion cocatalyst complexes poses a problem because itleaves labile, anionic-charge-carrying species as a byproduct within theresulting polymeric resins or matrices. These mobile anions adverselyaffect both dielectric strength and dielectric constant.

[0008] Additionally, olefin solution polymerization processes aregenerally conducted in aliphatic solvents that serve both to maintainreaction temperatures and solvate the polymer products. Butaryl-group-containing catalysts, those having cyclopentadienylderivatives and other fused or pendant aryl-group substituents, aresparingly soluble in such solvents and typically are introduced in thearyl solvents such as toluene. Because of health concerns, the arylsolvent must be removed. Also, aryl solvents reduce process efficienciesmaking their presence undesirable. Alternatively, relatively insolublecatalysts can be introduced using slurry methods, but such methodsrequired specialized handling and pumping procedures that complicateindustrial scale plant design and add significant costs to plantoperation. Typical slurry compositions cause significant wear on pumps,piping, joints, and connectors. Low solubility also poses a problem whenthe processes involve low temperature operation at some stage such astypically seen in adiabatic processes run in colder climates. Theadiabatic reactor is operated at ambient temperature. Thus, thecatalyst's low solubility is further lowered by a colder reactiontemperature. Additionally, counteracting the build-up of aryl solventsin the recycle system, or separating them from the system, presentsadded problems. At the same time, maintaining high molecular weights inolefin polymers while operating at economically preferable high reactiontemperatures and high production rates is highly desirable.

INVENTION DISCLOSURE

[0009] In part, this invention is a method for preparing olefinpolymers. The method includes contacting olefin monomers with a catalystsystem containing Group-3 to -11 metal-cation complexes that are surfacebound to a substrate. The substrate is finely divided particles that canbe effectively suspended in or solvated by reaction solvents ordiluents. Thus, the invention, in part, relates to a process forpreparing olefin-polymerization-catalyst compositions that containparticulate or polymeric support material connected to the catalystactivator and a Group 3-11, metal-catalyst-precursor compound that canbe activated for olefin polymerization. One goal is to substantiallyimmobilize the activator so that after activation, the resultingnon-coordinating anion and the catalyst are trapped within thesubstrate. Another goal is to modify the catalyst system so that it issoluble in the aliphatic polymerization solvent, or if not soluble,suspendable in the solvent such that the abrasive effect (as well asother negative effects faced in slurry polymerization) is substantiallyeradicated. This is done to prevent ion-based conduction in theresulting polymer. Additionally, the invention includes the polymerproducts prepared by the invention processes, particularlyethylene-containing polymers having insignificant levels of mobile,negatively charged particles as detectable by Time-of-Flight SIMSspectra.

[0010] Furthermore, the inventor also relates to the cocatalyst andcatalyst system compositions using support-bound cocatalysts.

DETAILED DESCRIPTION AND EXAMPLES OF THE INVENTION

[0011] The advantages of olefin solution polymerization generally, andethylene polymerization particularly, can be effectively extended by useof the invention process. The suspended, supported catalysts will meetthe solution process requirements of pumpability and dispersability inthe polymerization medium. Thus, the high activities or productivitiesenabled by systems based on aryl-group-containing catalysts andcocatalysts can be readily achieved without leaving noncoordinating orweakly coordinating anion residue in the polymer resins. Additionally,difficulties associated with using bulky-ligand-containing,organometallic, catalyst and cocatalyst activator compounds in which thepresence of aryl- and haloaryl-group ligands (such as, phenyl,perfluorophenyl, napthyl, perfluoronapthyl, cyclopentadienyl, indenyl,fluorenyl, etc.) inhibit aliphatic solvent solubility can be overcomeusing the invention's supported catalyst and cocatalyst compoundsbecause the compounds are easily suspendable in aliphatic solvents.

DESCRIPTION OF SUPPORT MATERIALS

[0012] Support material suitable for use with the invention can be anyof the inorganic oxide or polymeric support materials that 1) have, orcan be treated to have, reactive functional groups for connecting orchemically binding the catalyst or cocatalyst and 2) are small enough orconstitutes such that they disperse or dissolve in aliphatic solvents.Some embodiments include finely divided substrate particles that areessentially colloidal in size, or more quantitatively, less than orequal to about 2 microns, and are substantially non-porous. Theparticles can be essentially pore-free since reaction exotherm controldepends more on the presence of the solution processes' solvent ordiluent.

[0013] Suitable support materials include commercially availablepyrogenic silicas, commonly called fumed silicas. A typical silicapreparation process uses vapor-phase hydrolysis of silicon tetrachlorideat around 1000° C. Other methods include SiO₂ vaporization, Sivaporization and oxidation, and high temperature oxidation andhydrolysis of silicon compounds such as silicate esters. Examplesinclude the Aerosil™ and Cab-O-Sil™ of Degussa and Cabot Corp.respectively. Even after high temperature preparation, these silicaproducts retain enough silanol groups to connect with the cocatalystprecursor. The silanol groups are nucleophilic. It is believed that theyreact with the Lewis-acidic, cocatalyst precursors, such astrisperfluorophenyl borane. Furthermore, the particles' near-colloidalsize permits dispersion in polymerization solvents and diluents, evenafter treatment with cocatalyst precursor compounds. In someembodiments, the treated particles form colloidal suspensions inaliphatic polymerization, or other compatible, solvents. Additionalsupport materials include metal or metalloid compounds, such as oxides,that comprise significant amounts of hydroxyl-group-containing silica orsilica equivalent. Examples include alumina, alumino-silicates, clays,talcs, or other silica-containing Group-14 metalloid-metal elementcompounds. R. P. H. Chang, J. M. Lauerhaus, T. J. Marks, U. C. Pernisz,“Silica Nanoparticles Obtained From a Method Involving a Direct CurrentElectric Arc in an Oxygen-Containing Atmosphere”, U.S. Pat. No.5,962,132, Oct. 5, 1999, describes methods of preparing silica particlesof less than 100 nm diameter. This patent is incorporated by referencefor the purposes of U.S. Patent Practice.

[0014] In some embodiments, polymeric supports include polystyrene gelsor beads having a 2 micron or less mesh size. It is believed thatinternals pores are unnecessary in some embodiments because the catalystor cocatalyst attaches to the bead or gel surface materials. Thesolution-based polymerization conditions help to eliminate particle sizeconcerns seen in typical gas phase or slurry polymerizations. Thus, insome embodiments, the surface area is less than about 300 m²/g, evenless than 200 m²/g as measured by single point nitrogen B.E.T. analysis(Brunauer, S., Emmett, P. H., Teller, E., JACS 1938, 60, 309). Thecocatalyst precursors can be attached using any means that permitsubstantial connection to the substrate. See for instance U.S. Pat. Nos.5,427,991, 5,643,847, 5,939,347, WO 98/55518 and co-pending U.S.application Ser. No. 09/351,983 filed Jul. 12, 1999 (Atty. Docket No.98B041). Each is incorporated by reference for purposes of U.S. patentpractice.

[0015] Additional support materials include the essentially amorphous orsemicrystalline aliphatic-solvent-soluble polyolefins, for example,ethylene-containing polymers that contain nucleophilic groups forreacting with Lewis acid cocatalyst precursors. Various means ofincorporating nucleophilic groups into these polymers such that theyreact with the Lewis acidic precursors are known in the art. See, U.S.Pat. Nos. 5,153,282, 5,427,991, and WO 98/55518. Some polymerembodiments, such as those from ethylene, α-olefin monomers, oroptionally containing non-conjugated diolefin comonomers grafted withmaleic anhydride, are suitable. After the treatment with the cocatalystor after reaction with transition metal catalyst precursor, thesubstrate polymer should be readily dispersible or dissolvable. Thismeans that the untreated substrate should contain little enoughcrosslinking so that it remains soluble or dispersible in thepolymerization solvent after treatment with the cocatalyst or catalystprecursor.

[0016] The silica-based support can be fluorinated after dehydration todecrease the number of catalyst-degrading, surface functionalities.Suitable fluoridating compounds are typically inorganic. They may be anythat contain fluorine as long as they do not contain a carbon atom. Someembodiments use inorganic fluorine-containing compounds such as NH₄BF₄,(NH₄)₂SiF₆, NH₄PF₆, NH₄F, (NH₄)₂TaF₇, NH₄NbF₄, (NH₄)₂GeF₆, (NH₄)₂SmF₆,(NH₄)₂TiF₆, (NH₄)₂ZrF₆, MoF₆, ReF₆, GaF₃, SO₂ClF, F₂, SiF₄, SF₆, ClF₃,ClF₅, BrF₅, IF₇, NF₃, HF, BF₃, NHF₂, and NH₄HF₂. Of these, ammoniumhexafluorosilicate and ammonium tetrafluoroborate are particularlyuseful.

[0017] Ammonium hexafluorosilicate and ammonium tetrafluoroboratefluorine compounds are typically solid particulates. A desirable methodof treating the support with the fluorine compound is to dry mix the twocomponents by simply blending at a concentration of from 0.01 to 10.0millimole F/g of support, desirably in the range of from 0.05 to 6.0millimole F/g of support, and most desirably in the range of from 0.1 to3.0 millimole F/g of support. The fluorine compound can be dry mixedwith the support either before or after their addition to support,dehydration, or calcination vessels. Accordingly, the fluorineconcentration present on the support is in the range of from 0.6 to 3.5wt % of support.

[0018] In another method, the fluorine is dissolved in a solvent such aswater and then the support is contacted with the fluorine-containingsolution. When water is used and silica is the support, it is desirableto use a quantity of water that is less than the total pore volume ofthe support.

[0019] Silica dehydration or calcination is not necessary beforereacting it with the fluorine compounds. Desirably, the reaction betweenthe silica and fluorine compound is carried out at a temperature of fromabout 100° C. to about 1000° C., and more desirably from about 200° C.to about 600° C. for about two to eight hours.

[0020] The term noncoordinating anion as used for the inventioncompounds is art-recognized to mean an anion that either does notcoordinate to the transition metal cation or that coordinates weaklyenough to be displaced by a neutral Lewis base. “Compatible”noncoordinating anions (NCA) are those which are not neutralized whenreacted with the catalyst precursor compounds. Further, the compatibleanion should not transfer anionic substituents or fragments to thecatalyst to form a neutral metal compound and a neutral NCA by-product.Noncoordinating anions useful with invention embodiments are those thatare compatible with or stabilize the invention transition metal cationby balancing its ionic charge, yet can be displaced by an olefinicallyunsaturated monomer during polymerization. Additionally, because theanions are support bound, it is believed that they have sufficient sizeto inhibit or prevent neutralization of the invention catalysts by anyextraneous Lewis bases present in the reaction. Suitable aryl ligandsfor the invention include those of the noncoordinating anions asdescribed in U.S. Pat. Nos. 5,198,401, 5,278,119, 5,407,884, and5,599,761. Specific examples include the phenyl, napthyl, andanthracenyl radicals of U.S. Pat. No. 5,198,401, the biphenyl radicalsof WO 97/29845, and the ligands of the noncoordinating anions of WO99/45042, preferably where a majority of ring-hydrogen atoms arereplaced with halogens. All documents are incorporated by reference forpurposes of U.S. patent practice. In some embodiments, the anions'sources are neutral, tri-coordinate Lewis acids that containaryl-substituted boron or aluminum, and that are reactive with thesupport material's nucleophilic groups, e.g., hydroxyl groups of thefumed silica or polymer substrate. Trisperfluorophenyl borate,trisperfluoronapthylborate, and trisperfluorobiphenylborate areexamples.

[0021] Invention, supported catalysts can be prepared by addingorganometallic, transition-metal catalyst-precursor compounds into awell-stirred or well-mixed solution or suspension of the fine-particle-or polymeric-supported cocatalysts long enough to allow the cocatalystto ionize the catalyst precursor into cationic catalysts. The catalystand cocatalyst reaction can be conducted at ambient temperature or canbe warmed to 40° C. or higher to facilitate the reaction. The reactionproduct is a catalytic, cationic metal complex connected to thesupport-bound noncoordinating or weakly coordinating anion. Thecatalyst-cocatalyst complex can then be directly added into a reactor,or can be dried or separated from the suspension for subsequentpolymerization.

[0022] Transition metal compounds suitable as polymerization catalystsin accordance with the invention include the known transition metalcompounds useful in traditional Ziegler-Natta polymerization and as wellthe metallocene compounds similarly known to be useful inpolymerization. The compounds are suitable when the invention cocatalystactivators can catalytically activate them. These typically includeGroup-3-11 transition metal compounds in which at least one metal ligandcan be protonated by the cocatalyst activators, particularly thoseligands including hydride, alkyl, and silyl, and lower alkyl-substituted(C₁-C₁₀) silyl or alkyl derivatives of those. Ligands capable ofabstraction and transition metal compounds comprising them include thosedescribed in the background art, see for example U.S. Pat. No. 5,198,401and WO 92/00333. Syntheses of these compounds are well known from thepublished literature. Additionally, where the metal ligands includehalide, amido, or alkoxy moieties (for example, biscyclopentadienylzirconium dichloride) that the invention cocatalysts can't abstract, themoieties can be converted into suitable ligands through known alkylationreactions with lithium or aluminum hydrides or alkyls, alkylalumoxanes,Grignard reagents, etc. See also EP-A1-0 570 982 for organoaluminumcompounds reaction with dihalo-substituted metallocene compounds beforeadding an activator. All documents are incorporated by reference forpurposes of U.S. patent practice.

[0023] Additional description of metallocene compounds that comprise, orcan be alkylated to comprise, at least one ligand capable of abstractionto form a catalytically active transition metal cation appear in thepatent literature, e.g., EP-A-0 129 368, U.S. Pat. Nos. 4,871,705,4,937,299, 5,324,800 EP-A-0 418 044, EP-A-0 591 756, WO-A-92/00333,WO-A-94/01471 and WO 97/22635. Such metallocene compounds are mono- orbiscyclopentadienyl-substituted Group-3, -4, -5, or -6 transition metalcompounds in which the ligands may themselves be substituted with one ormore groups or may bridge to each other or to the transition metalthrough a heteroatom. The size and constituency of the ligands andbridging elements are not critical to preparing the invention catalystsystems, but should be selected in the literature-described manner toenhance the desired polymerization activity and polymer characteristics.In some embodiments, the cyclopentadienyl rings (including substitutedcyclopentadienyl-based fused-ring systems, such as indenyl, fluorenyl,azulenyl, or their substituted analogs), when bridged to each other,will be lower-alkyl-substituted (C₁-C₆) in the 2 position (with orwithout a similar 4-position substituent in the fused-ring systems) andmay additionally comprise alkyl, cycloalkyl, aryl, alkylaryl, orarylalkyl substituents, the latter as linear, branched, or cyclicstructures including multi-ring structures, for example, those of U.S.Pat. Nos. 5,278,264 and 5,304,614. Such substituents should each haveessentially hydrocarbyl characteristics and will typically contain up to30 carbon atoms, but may be heteroatom-containing with 1-5 non-hydrogenor carbon atoms, e.g., N, S, O, P, Ge, B and Si. All documents areincorporated by reference for purposes of U.S. patent practice.

[0024] Metallocene compounds suitable for the preparation of linearpolyethylene or ethylene-containing polymers (where copolymer meansformed from at least two different monomers; for this disclosure,“polymer” completely encompasses all varieties of homo-, hetero,copolymers) are essentially any of those known in the art, see againWO-A-92/00333 and U.S. Pat. Nos. 5,001,205, 5,198,401, 5,324,800,5,304,614 and 5,308,816, for specific listings. Selection of metallocenecompounds for use to make isotactic or syndiotactic polypropylene, andtheir syntheses, are well-known in both the patent and academicliterature, see for example Journal of Organometallic Chemistry, 369,359-370 (1989). Typically, those catalysts are stereorigid, asymmetric,chiral, or bridged-chiral metallocenes. See, for example, U.S. Pat. No.4,892,851, U.S. Pat. No. 5,017,714, U.S. Pat. No. 5,296,434, U.S. Pat.No. 5,278,264, WO-A-(PCT/US92/10066) WO-A-93/19103, EP-A2-0 577 581,EP-A1-0 578 838, and academic literature “The Influence of AromaticSubstituents on the Polymerization Behavior of Bridged ZirconoceneCatalysts”, Spaleck, W., et al, Organometallics 1994, 13, 954-963, and“ansa-Zirconocene Polymerization Catalysts with Annelated RingLigands-Effects on Catalytic Activity and Polymer Chain Lengths”,Brinzinger, H., et al, Organometallics 1994, 13, 964-970, and documentsreferred to in the references. Although these references are directed tocatalyst systems with alumoxane activators, some analogous precursorswill be useful with invention cocatalyst activators. A suitable catalystprecursor typically has 1) one or more ligands that have been replacedwith an abstractable ligand; and 2) one or more ligands into which anethylene group, —C═C—, can insert. Examples include hydride, alkyl, orsilyl. All documents are incorporated by reference for purposes of U.S.patent practice.

[0025] Some representative metallocene compounds have the formula:

L ^(A) L ^(B) L ^(C) _(i) MDE

[0026] where, L^(A) is a substituted cyclopentadienyl orheterocyclopentadienyl ligand connected to M; L^(B) is a member of theclass of ligands defined for L_(A), or is J, a heteroatom ligandconnected to M; the L^(A) and L^(B) ligands may be connected togetherthrough a Group-14-element linking group; L^(C) _(i) is an optionalneutral, non-oxidizing ligand connected to M (i equals 0 to 3); M is aGroup-4 or -5 transition metal; and, D and E are independentlymonoanionic labile ligands, each connected to M, optionally connected toeach other or L^(A) or L^(B), in which the connection can be broken by asuitable activator and into which a monomer or macromonomer can insertfor polymerization.

[0027] Non-limiting representative metallocene compounds includemono-cyclopentadienyl compounds such aspentamethylcyclopentadienyltitanium isopropoxide,pentamethylcyclopentadienyltribenzyl titanium,μ-dimethylsilyltetramethylcyclopenta-dienyl-tert-butylamido titaniumdichloride, pentamethylcyclopentadienyl titanium trimethyl,dimethylsilyltetramethylcyclopenta-dienyl-tert-butylamido zirconiumdimethyl, dimethylsilyltetramethylcyclopentadienyl-dodecylamido hafniumdihydride, dimethylsilyltetramethylcyclopentadienyl-dodecylamido hafniumdimethyl, unbridged biscyclopentadienyl compounds such as bis(1,3-butyl,methylcyclopentadienyl) zirconium dimethyl,pentamethylcyclopentadienyl-cyclopentadienyl zirconium dimethyl,(tetramethylcyclopentadienyl)(n-propyl-cyclopentadienyl)zirconiumdimethyl; bridged bis-cyclopentadienyl compounds such asdimethylsilylbis(tetrahydroindenyl) zirconium dichloride andsilacyclobutyl(tetramethylcyclopentadienyl)(n-propyl-cyclopentadienyl)zirconium dimethyl; bridged bis-indenyl compounds such asdimethylsily-bisindenyl zirconium dichloride, dimethylsily-bisindenylhafnium dimethyl, dimethylsilylbis(2-methylbenzindenyl) zirconiumdichloride, dimethylsilylbis(2-methylbenzindenyl) zirconium dimethyl;and fluorenyl ligand-containing compounds, e.g.,diphenylmethyl(fluorenyl)(cyclopentadienyl)zirconium dimethyl; and theadditional mono- and biscyclopentadienyl compounds such as those listedand described in U.S. Pat. Nos. 5,017,714, 5,324,800 and EP-A-0 591 756.All documents are incorporated by reference for purposes of U.S. patentpractice.

[0028] Representative traditional Ziegler-Natta transition metalcompounds include tetrabenzyl zirconium, tetra bis(trimethylsilylmethyl)zirconium, oxotris(trimethylsilylmethyl) vanadium, tetrabenzyl hafnium,tetrabenzyl titanium, bis(hexamethyl disilazido)dimethyl titanium,tris(trimethyl silyl methyl) niobium dichloride,tris(trimethylsilylmethyl) tantalum dichloride. The important featuresof such compositions for polymerization are the ligands capable ofabstraction and the ligands into which the ethylene (olefinic) group caninsert. These features enable ligand abstraction from the transitionmetal compound and the concomitant formation of the invention ioniccatalyst compositions.

[0029] Additional transition metal polymerization catalysts inaccordance with the invention will be any of those Group-3-10 compoundsthat can be converted by ligand abstraction into a catalytically activecation and stabilized in that state by a noncoordinating or weaklycoordinating anion, as defined above.

[0030] Exemplary compounds include those described in the patentliterature. International patent publications WO 96/23010, WO 97/48735and Gibson, et. al., Chem. Comm., pp. 849-850 (1998), disclosediimine-based ligands for Group 8-10 metal compounds shown to besuitable for ionic activation and olefin polymerization. See also WO97/48735. Transition-metal catalyst systems from Group 5-10 metals inwhich the active transition metal center is in a high oxidation stateand stabilized by low coordination number, polyanionic ancillary ligandsystems are described in U.S. Pat. No. 5,502,124 and its divisional U.S.Pat. No. 5,504,049. See also the Group-5 organometallic catalystcompounds of U.S. Pat. No. 5,851,945 and thetridentate-ligand-containing, Group 4-9 organometallic catalystcompounds of copending U.S. application Ser. No. 09/302243, filed Apr.29, 1999, and its equivalent PCT/US99/09306. Group-11 catalyst precursorcompounds, activated with ionizing cocatalysts, and useful forpolymerizing of olefins and vinyl-group-containing polar monomers aredescribed and exemplified in WO 99/30822 and its priority document,including U.S. Pat. No. application Ser. No. 08/991,160, filed Dec. 16,1997. Each of these documents is incorporated by reference for thepurposes of U.S. patent practice.

[0031] U.S. Pat. No. 5,318,935 describes bridged and unbridged bisamidotransition-metal compounds of Group-4 for olefin polymerizationcatalysts are described by D. H. McConville, et al, in Organometallics1995, 14, 5478-5480. Further work appearing in D. H. McConville, et al,Macromolecules, 1996, 29, 5241-5243, described bridged bis(arylamido)Group-4 compounds that are active catalysts for polymerization of1-hexene. See also WO 98/37109. Additional transition metal compoundssuitable for invention embodiments include those described in WO96/40805. Cationic Group-3 or Lanthanide metal complexes for olefinpolymerization are disclosed in copending U.S. application Ser. No.09/408050, filed Sep. 29, 1999 (Atty. Docket No. 98B054), and itsequivalent PCT/US99/22690. The precursor compounds are stabilized bymonoanionic bidentate ligands and two monoanionic ligands. Inventioncocatalysts can activate these precursor compounds. Each of thesedocuments is incorporated by reference for the purposes of U.S. patentpractice.

[0032] Additional catalyst precursors are described in the literature,any of which are suitable where they contain, or can be modified tocontain, ligands capable of being abstracted for ionization of theorganometallic compounds. See, for instance, V. C. Gibson, et al, “TheSearch for New-Generation Olefin Polymerization Catalysts: Life BeyondMetallocenes”, Angew. Chem. Int. Ed., 38, 428-447 (1999), incorporatedby reference for the purposes of U.S. patent practice.

[0033] When using the invention catalysts, particularly when they aresupport bound, the total catalyst system will optionally contain one ormore scavenging compounds. The term “scavenging compounds” as used inthis application includes compounds that remove polar impurities(catalyst poisons) from the reaction environment. Impurities can beintroduced with the reaction components, particularly solvent, monomer,and catalyst feeds. These impurities vitiate catalyst activity andstability, particularly when ionizing-anion-precursors activate thecatalyst system. These impurities include water, oxygen, metalimpurities, etc. Typically, they are limited or eliminated beforeintroducing the reaction components into the vessel, but some scavengingcompound will normally be used in the polymerization process.

[0034] Typically, the scavenger will be an excess of the alkylated Lewisacids needed for activation, as described above, or will be knownorganometallic compounds such as the Group-13 organometallic compoundsof U.S. Pat. Nos. 5,153,157, 5,241,025, 5,767,587 and WO-A-91/09882,WO-A-94/03506, WO-A-93/14132, and that of WO 95/07941. Exemplarycompounds include triethyl aluminum, triethyl borane, triisobutylaluminum, methylalumoxane, isobutyl aluminumoxane, and tri-n-octylaluminum. Those scavenging compounds having bulky or C₆-C₂₀ linearhydrocarbyl substituents bound to the metal or metalloid center minimizeadverse scavenger interaction with the active catalyst. Examples includetriethylaluminum, but more preferably, bulky compounds such astriisobutylaluminum, triisoprenylaluminum, and long-chain linearalkyl-substituted aluminum compounds, such as tri-n-hexylaluminum,tri-n-octylaluminum, or tri-n-dodecylaluminum. Alumoxanes also may beused in scavenging amounts with other activation methods, e.g.,methylalumoxane and triisobutyl-aluminoxane. The amount of scavengingagent to be used with the invention Group 3-10 catalyst compounds isminimized to the amount that enhances activity and is omitted altogetherif the feeds and polymerization medium are pure enough.

[0035] Some catalyst embodiments are useful with polymerizable monomers.Suitable conditions are well known and include solution polymerization,slurry polymerization, and high-pressure polymerization. The inventioncatalyst is supported as described and will be particularly useful inthe known reactor operating modes employing fixed-bed, moving-bed,fluid-bed, slurry, or solution processes conducted in single, series, orparallel reactors.

[0036] The liquid processes comprise contacting olefin monomers with theabove-described catalyst system in a suitable diluent or solvent andallowing those monomers to react long enough to produce the inventioncopolymers. Both aliphatic and aromatic hydrocarbyl solvents aresuitable; aliphatic solvents such as cyclopentane or hexane are used insome embodiments. In bulk and slurry processes, catalysts are typicallybrought into contact with a liquid monomer slurry, such as propylene, ormonomer in a liquid diluent, such as ethylene in 1-hexene or 1-octene inn-butane. Representative reaction temperatures and pressure fordifferent embodiments are shown in Table I. TABLE I Reaction Temperatureand Reaction Pressure Embodiment Reaction Temperature in ° C. A ≦220 B≧40 C ≦250 D ≧60 Reaction Pressure in bar E ≦2500 F ≧0.1 G ≦500 H ≦1600I ≧1.0 J ≧0.001

[0037] Linear polyethylene, including high- and ultra-high-molecularweight polyethylenes, including both homo- and copolymers with otherα-olefin monomers, α-olefinic or non-conjugated diolefins, for example,C₃-C₂₀ olefins, C₅-C₂₀ diolefins, C₇-C₂₀ vinyl aromatic monomers (suchas styrene) or C₅-C₂₀ cyclic olefins, are produced by adding ethylene,and optionally one or more other monomers, to a reaction vessel, or morethan one vessel in parallel or series, under low pressure (typically <50bar), at a typical temperature of 40-250° C. These are placed togetherwith invention, supported catalysts suspended in a solvent or diluent,such as hexane or toluene. Cooling typically removes polymerizationheat. See, U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670 and 5,405,922and 5,462,999, which are incorporated by reference for purposes of U.S.patent practice.

[0038] Semicrystalline polypropylenes can also be prepared with theinvention process, particularly those having 0.1-30 mol %, morepreferably 7-25 mol %, of ethylene or higher α-olefins. Polymers havingsufficient ethylene or other comonomer content to render themsubstantially soluble in hexane are particularly suitable forpreparation in stirred-tank reactors, tubular reactors, or anycombination of stirred-tank or tubular reactors in parallel or seriesoperation with the invention catalysts.

[0039] High molecular weight, low crystallinity ethylene-α-olefinelastomers (including ethylene-cyclic-olefin andethylene-α-olefin-diolefin) can be prepared using invention catalystsunder traditional solution polymerization processes or by introducingethylene gas into a slurry using α-olefin, cyclic olefin, or theirmixtures with other compounds, polymerizable or not, as diluents forsuspending invention catalysts. Typical ethylene pressures will bebetween 10 and 1000 psig (69-6895 kPa), and the diluent temperature willtypically be between 40 and 160° C. The process can be carried out in astirred tank reactor, or more than one operated in series or parallel.See the general disclosure of U.S. Pat. No. 5,001,205 for generalprocess conditions. See also, International Applications WO 96/33227 andWO 97/22639. All documents are incorporated by reference for purposes ofU.S. Patent Practice.

[0040] Some invention process embodiments are particularly applicable tosubstantially adiabatic, homogeneous solution polymerization. Adiabaticprocesses are those in which polymerization heat is accommodated byallowing a temperature rise in the reactor contents, here principallysolvent or diluent. Typically, in these processes, no internal coolingis absent and external cooling is unnecessary. The reactor outlet streamremoves reaction heat from the reactor. Cooling the solvent or monomerstream(s) before they enter these reactors improves productivity becauseit permits a greater polymerization exotherm. Thus, the catalyst,cocatalyst, and scavenger selections disclosed in this application canbe advantageously practiced in a continuous, solution process operatedat or above 140° C., above 150° C. or above 160° C., up to about 250° C.Typically, this process is conducted in an inert linear, cyclic orbranched aliphatic or aromatic solvent, at a pressure of from 10 to 200bar. These catalysts' provision of desirable polymer at elevatedtemperatures contributes to a greater exotherm, to high polymer contentin the reactor because of lower viscosity, to reduced energy consumptionin evaporating and recycling solvent, and to better monomer andcomonomer conversions. See, for example, U.S. Pat. No. 5,767,208, andco-pending U.S. application Ser. No. 09/261,637, filed Mar. 3, 1999, andits equivalent WO 99/45041, all of which are incorporated by referencefor purposes of U.S. patent practice.

[0041] Ethylene-containing polymers for electrical devices are describedmore particularly in the literature. See, for example, U.S. Pat. Nos.5,246,783, 5,763,533, and International Publication WO 93/04486. Each ofthese polymers can be prepared in the manner described in the precedingparagraphs. Other olefinically-unsaturated monomers besides thosespecifically described in these documents may be polymerized using theinvention catalysts as well, for example, styrene, alkyl-substitutedstyrenes, isobutylene, and other geminally-disubstituted olefins,ethylidene, norbornene, norbornadiene, dicyclopentadiene, and otherolefinically-unsaturated monomers, including other cyclic olefins, suchas cyclopentene, norbornene, and alkyl-substituted norbornenes. See, forexample, U.S. Pat. Nos. 5,635,573, and 5,763,556. Additionally,α-olefinic macromonomers of 1000 mer units or more, may also becomonomers yielding branch-containing polymers. Each of the foregoingreferences are incorporated by reference for their relevant teachings.

[0042] Invention catalysts can function individually or can be mixedwith other catalyst to form a multi-component system. Monomer andcoordination-catalyst-blend selection yield polymer blends preparedunder conditions analogous to those using individual catalysts. Polymershaving increased MWD for improved processing and other traditionalbenefits available from polymers made with mixed catalyst systems canthus be achieved.

[0043] Blended polymer formation can be achieved ex situ throughmechanical blending or in situ through the use of mixed catalysts.Generally, in situ blending provides a more homogeneous product andallows one-step blend production. In situ blending using mixed catalystsinvolves combining more than one catalyst in the same reactor tosimultaneously produce multiple, distinct polymer products. This methodrequires additional catalyst synthesis. Moreover, the catalystcomponents must be matched for the polymer products they generate atspecific conditions and for their response to changes in polymerizationconditions.

[0044] The following examples are presented to illustrate the foregoingdiscussion. All parts, proportions and percentages are by weight unlessotherwise indicated. All examples were carried out in dry, oxygen-freeenvironments and solvents. Although the examples may be directed tocertain embodiments of the present invention, they do not limit theinvention in any specific respect.

EXAMPLES

[0045] Materials

[0046] Toluene was purged with N₂ for 5 min, then dried over molecularsieves overnight. The toluene was poured down a basic-Al₂O₃ columnbefore use. Tris(pentafluorophenyl)boron from Aldrich was dissolved inpentane and filtered with a 0.45 μm filter. It was recrystallized fromn-pentane in a freezer and vacuum dried at room temperature.Diethylaniline from Aldrich was dried over CaH₂ overnight and passedthrough a basic-Al₂O₃ column before use. 1-hexene was dried over CaH₂overnight and similarly passed through a basic-Al₂O₃ column before use.

Example A

[0047] Cabosil was prepared by heating for 400° C. for 48 hrs followedby heating under vacuum at 200° C. for 6 hours. 0.54 g of the Cabosilwas added to 30-40 mL dried toluene. 86 μL of prepared diethylanilinewas added and stirred for 5 min. 0.2762 g of the recrystallizedtris(pentafluorophenyl)boron was dissolved in 3 ml toluene and thenslowly added to the silica-containing toluene solution. This mixture wasstirred for 30 min at room temperature and then allowed to settleovernight. The toluene layer was removed by pipette and the wet slurrywas dried under vacuum at room temperature to a produce a dry,free-flowing powder. The yield of silica-bound activator (SBA) was0.6555 g

[0048] Catalyst Preparation

[0049] 263.88 mg of SBA was suspended in toluene and added to a toluenesolution of 90.7 mg of μ-diphenylmethylene (cyclopentadienyl)(fluorenyl) hafnium dimethyl. The mixture was stirred for 30 min at roomtemperature. The resulting supported catalyst was vacuum dried at roomtemperature.

[0050] Polymerization I

[0051] In a dry box, a portion of a small spatula full of the supportedcatalyst prepared above was placed in a dried 20-mL vial. Approximately5 mL of dried hexene-1 (passed through a basic-alumina column) was addedto the vial in liquid form. After a short period of time, the vialbecame hot and the liquid became notably viscous. On completion, thehexene-1 polymerized to sufficient molecular weight that the viscousmass flowed only sluggishly when the vial was turned upside down. A fewdays after polymerization, the nonporous, pinkish orange, supportedcatalyst settled out from the polymer solution, leaving a clear solutionbehind. Further fractionation can allow for substantial separation ofpolymer from catalyst residue. Subsequent analysis by LDMS and ToF-SIMSshowed insignificant labile anion presence, for both the separatedpolymer portion, and that with entrained residual catalyst. (Such use inthe suspension polymerization of polypropylene so that with or withoutcatalyst residue removal, effective grades for electrical gradepolypropylene products, for example, capacitor grade polypropylene canbe produced.)

Example B Preparation of Cabosil 700

[0052] The silica was heated under a flow of dry nitrogen gas. Aprogrammable temperature controller was used to run the temperatureprofile shown in the table below. Temperature (° C.) Time (min)  25 to105  48 105 to 160 132 160 to 700 263 700 240 700 to 25  120

Example C SBA-700 Preparation

[0053] 2.669 g of Cabosil-700, prepared as in Example B, was suspendedin 80 mL or toluene dried as described above. A solution of 0.106 μL DEAthat had been diluted in 0.9 mL toluene was added. This mixture wasstirred for 10 min at room temperature. A solution of 342 mg B(C6F5)3dissolved in 5 mL of toluene at room temperature was added. The productwas filtered from solution and washed with 80 mL of toluene. Thefiltering/washing steps were repeated two times. The product was vacuumdried at room temperature to a dry, free-flowing powder.

Example D Catalyst Preparation

[0054] 98.6 mg of SBA-700, produced in Example C, was slurried in 2.8 mLtoluene. 3.74 mL of 6 mMrac-dimethylsilylbis(3-methyl-4-phenyl-indenyl)Zirconium X₂ in toluenewas added to the SBA slurry. The mixture was stirred for 5 minutes. Theproduct was filtered and then vacuum dried at room temperature.

Example E

[0055] Polymerization II

[0056] 0.3 mL of one-tenth diluted TIBAL (in toluene) was placed into asteam dried 2L reactor. 300 mL of liquid propylene was added to thereactor. The reactor was then heated to 60° C. 100 mg of the Catalyst ofExample D was flushed into the reactor with 100 mL of propylene. Thepolymerization was run for 30 minutes. The reactor was cooled andvented. The polymerization yielded 43.3 g of dried polypropylene(catalyst activity 7.81×10⁶ g/mol-hr).

Comparative Examples and Experimental Data

[0057] Experimental data for LDMS and ToF-SIMS analyses of a series ofEP copolymers made using soluble rac-dimethylsilyl bis(indenyl) hafniumdimethyl and [dimethylanilinium]⁺[tetrakis(pentafluorophenyl)borate]⁻activator in a 1.0 L. continuous flow stirred tank reactor. All thepolymerizations were carried out using between 13 and 97 equivalents ofTIBAL. All polymerizations conducted at 110° C. with reactor residencetime of 12.8 to 15.0 min.

[0058] Polymerization Procedure (Single Reactor)

[0059] Polymerizations were carried out in one, one-liter stirredreactor with continuous flow of feeds to the system and continuouswithdrawal of products. The solvent was hexane. Monomers were ethyleneand propylene, and were purified over beds of alumina and molecularsieves. All feeds were pumped into the reactors by metering pumps exceptfor the ethylene (and hydrogen where applicable), which flowed as a gasunder its own pressure through a mass flow meter/controller. Circulatingwater through a reactor-cooling jacket controlled reactor temperature.The reactors were maintained at a pressure in excess of the vaporpressure of the reactant mixture to keep the reactants in the liquidphase. The reactors were operated liquid full.

[0060] Ethylene and propylene feeds were combined into one stream andthen mixed with a hexane stream that had been cooled to 0° C. A hexanesolution of triisobutyl aluminum scavenger was added to the combinedsolvent and monomer stream just before it entered the reactor to furtherreduce the concentration of any catalyst poisons. The catalystcomponents in solvent (usually toluene or toluene/hexane mixtures) wereseparately pumped to the reactor and, in most cases, activated in-linejust before the reactor, then the activated catalyst entered the reactorthrough a separate port outfitted with a dip tube to ensure adequatedistribution. The polymer/solvent/unconverted monomers and catalystsolution exit the first reactor through a pressure control valve thatreduced the pressure to atmospheric. This caused the unconvertedmonomers in the solution to flash into a vapor phase. The gas was ventedfrom the top of a vapor-liquid separator. The liquid phase, including,for the most part, polymer and solvent, flowed out the bottom of theseparator and was collected for polymer recovery. After removing a smallportion for determining cement concentration, stabilizer was added tothe polymer solution. The stabilized polymer was recovered from solutionby either steam stripping followed by vacuum drying, or by solventevaporation over heat and vacuum drying. Some comparative polymerizationdata are summarized in Table 1. TABLE 1 Summary of EP CopolymersAnalyzed Catalyst Polymer Wt. Avg. Eff Est. wppm Scav/Cat Wt % MWSamples (g/g) of B(C₆F₅)₄ (mol/mol) C₂ (GPC) AA 17757 32 33 63.8 202,000BB 11607 50 70.3 70.6 272,000 CC 24509 22 13.2 58.6 166,000 DD  4810120  97.1 72.9 288,000

[0061] All four samples were analyzed by LDMS and ToF-SIMS. In all casesthe B(C₆F₅)₄ anion was readily detected. The match of peak intensitiesand masses with those calculated for B(C₆F₅)₄ anion established itsidentity. All mass spectra were recorded using a PHI-Evans triple sectorelectrostatic analyzer time-of-flight mass spectrometer equipped withdual multichannel plate detector, ¹¹⁵In ion gun and nitrogen laser(λ=337 nm). The ion gun was operated at 15 keV and 600 pA. For LDMS,100-300 laser shots were used to acquire the spectrum. Laser power was˜10⁷ watts/cm². External and internal mass calibration was carried outusing a variety of known molecular standards and identities ofwell-established peaks in each mass spectrum.

[0062] Samples were prepared for analysis in two ways. In the first, aportion of the polymer was extracted with 5 mL of 90° C. toluene. Afterextraction for about 10 min. in a glass vial, approximately 1 μL of thesolution was deposited on a clean silicon wafer. In the second, aportion of polymer was cross-sectioned to expose the interior, and thefreshly exposed surface was analyzed directly.

[0063] Use of known masses and isotope distributions of relevantelements, below, B 10.0129 (19.7%) 11.0093 (80.3%) C 12.0000 (98.89%)13.00335 (1.11%) F 18.9984 (100%)

[0064] with the stoichiometry of the [B(C₆F₅)₄]⁻ anion results in thecalculated values below.

B(C ₆ F ₅)₄

[0065] Mass 677.98 678.97 679.98 680. Intensity, % 23 100 23 3

[0066] The negative ion LDMS mass spectrum of the pure [DMAH][B(C₆F₅)₄]salt provided two major peaks, one at m/z=679 due to the intact B(C₆F₅)₄anion, and a second at 167 due to (C₆F₅)⁻. Along with peaks due toadditives and copolymer, a fingerprint at m/z=679 was observed. The 600to 700 region of this spectrum clearly showed that the peak nominally atm/z 679 in fact consisted of four peaks. These peaks are due to thecontributions of ¹⁰B (abundance 19.7%) and ¹³C (abundance 1.11%)isotopes to the mass spectrum of the Samples of Table 1. There was anexcellent match between the experimentally measured and calculatedintensities of the peaks due to the isotope contributions. Such anexcellent match between calculated and measured isotope patterns wasfound in all the m/z=679 spectra for the pure salt and the Samples. Inaddition to the isotope pattern match, the exact mass measured for eachof the four peaks in all the spectra also matched, within experimentalerror, those calculated for the B(C₆F₅)₄ anion.

[0067] In contrast, similar LDMS and ToF-SIMS analysis of isotacticpolypropylene prepared with a supported catalyst made in accordance withprocedures of reported Example 9 of U.S. Pat. No. 5,643,847, and havingthe support bound anion as described therein, did not contain signaturesof any B(C₆F₅)_(x) anions, where x specifically includes 3 or 4. Thus,using reference procedures, no evidence of the anion can be found in theinvention support bound cocatalysts. Yet, anion can be found in systemsthat do not use support bound cocatalysts. See, e.g. P. Brant, K.-J. Wu“Detection of B(C6F5)4 anions in polyethylenes made with ionicmetallocene catalysts.” Journal of Materials Science Letters 19 (2000)189-191.Therefore, the dielectric advantages of the supported catalystof this ionic catalyst supporting technique can be extended from thetaught gas phase and slurry polymerization processes to solutionpolymerization processes when using the support substrate materials ofthis application.

I claim: What is claimed is:
 1. An electrical device comprising at leastone polyolefin resin containing negatively charged, residual anioniccocatalyst complexes, wherein the resin has insignificant levels ofmobile, negatively charged particles as detectable by Time of FlightSIMS.
 2. The device according to claim 1 wherein the resin has beenprepared by contacting olefin monomers under polymerization conditionswith an organometallic catalyst compound activated with a support-bound,noncoordinating or weakly coordinating anion, in which the support isfinely divided substrate particles or polymer capable of effectivesuspension or solvation in polymerization solvents or diluents.
 3. Themethod of claim 2 wherein the support comprises pyrogenic silica,alumina, alumino-silicates, or silica-containing Group-14metal/metalloid element compounds.
 4. The device according to claim 2wherein the support comprises essentially hydrocarbyl polymer.
 5. Thedevice according to claim 2 wherein the polymerization conditions areessentially solution- or supercritical-phase conditions.
 6. The deviceaccording to claim 1 or 2 wherein the resin is an elastomeric,ethylene-containing polymer.
 7. The device according to claim 6 whereinthe polymer comprises monomeric units derived from C₃-C₁₂ olefins. 8.The device according to claim 7 wherein the olefins are at least one ofpropylene, 1-butene, isobutylene, 1-hexene, norbornene, styrene and1-octene.
 9. The device according to claim 7 or 8 wherein the polymeradditionally comprises units derived from at least one non-conjugateddiolefin.
 10. The device according to claim 9 wherein the non-conjugateddiolefin is one of dicyclopentadiene, 1,4-hexadiene, ethylidenenorbornene, or vinyl norbornene.
 11. The device according to claim 10wherein the olefin is propylene.
 12. The device according to claim 1 or2 wherein the resin is a semicrystalline or crystalline polymer whereinthe polymer contains ethylene-derived monomeric units.
 13. The deviceaccording to claim 12 wherein the polymer comprises monomeric unitsderived from C₃-C₁₂ olefins.
 14. The device according to claim 13wherein the olefins are propylene, 1-butene, isobutylene, 1-hexene,norbornene, styrene, 4-methyl-1-pentene, or 1-octene.
 15. The deviceaccording to claim 14 wherein the olefins are 1-butene, 1-hexene, and1-octene.
 16. An electrical device comprising at least one polyolefinresin wherein the resin has been prepared by contacting olefin monomersunder polymerization conditions with an activated, Group-3-11organometallic catalyst compound that has been activated with asupport-bound noncoordinating or weakly coordinating borate or aluminateanion, wherein the support is finely divided substrate particles orpolymer chains capable of effective suspension in polymerizationsolvents or diluents.
 17. The device according to claim 16 wherein thesupport comprises pyrogenic silica.
 18. The device according to claim 16wherein the support comprises essentially hydrocarbyl polymer chains.19. The device according to claim 16 wherein the hydrocarbyl polymerchains are comprised of units derived from olefins.
 20. The deviceaccording to claim 19 where the hydrocarbyl chains are soluble inaliphatic solvents.
 21. The device according to claim 16 wherein thepolymerization conditions are essentially solution- orsupercritical-phase conditions.
 22. The device according to claim 16wherein the organometallic catalyst compound is a Group-3-6 metalcompound containing a cyclopentadienyl-group.
 23. The device accordingto claim 22 wherein the metal is titanium and the metal compoundcontains only one pi-bound cyclopentadienyl group.
 24. The deviceaccording to claim 22 wherein the metal compound comprises at least onebiscyclopentadienyl zirconium or hafnium compound.
 25. The deviceaccording to claim 16 wherein the resin contains units derived fromethylene.
 26. The device according to claim 25 wherein the resin is anethylene polymer comprising monomer units derived from at least one ofC₃-C₁₂ olefins or non-conjugated diolefins.